Method of producing metal tubes



Nov. 13, 1928. 1,691,725

- W. LEIGHTON METHOD OF PRODUCING METAL TUBES Filed Sept. 30, 1926 75.43 L m 7 L15 I 5 s a lnvehtor.

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Patented Nov. 1 3, 1928.

Joint wxcmrrn LEIGI-ITON", or roar URON, MICHIGAN.

" mn'rnon or raonucme marlin TUBES.

Application filed September 30, 1926. Serial No. 188,675.

The principal objects of the invention are, to enable the production ofmetal tubes by extrusion in large quantities and at low cost, and todevise a simple and effective means 5 for extruding metal billets.

The principal feature of the invention consists in the novel method ofpartly extruding the metal of the billet from a die and completing theoperation by the progressive extrusion ofa portion of the succeedingbillet.

In the drawings, Fi ure 1 is an elevational part sectional view of a setof dies showing a partly extruded billet and a heating torch arrangedtoapply heat to the partly ex- 1 truded billet.

Figure 2 is an elevational part sectional view of a-set of dies showinga succeeding billet placed therein upon a partly extruded billet. r

Figure 3 is an elevational part sectional view of the dies showing thesucceeding billet partly extruded and completing the extrus1on of thepreceding billet.

In the manufacture of short length tubin from prepared billets byextrusion method%,, numerous forms have been devised but diflicultieshave been encountered in the maintenance of the tools and in properclearing of the dies after each operation. he

present method overcomes the objections that have been met with.

In the method of extruding billets to form tubes it has been foundnecessary to form the die with a bevelled bottom wall so that the metalmay flow smoothly into the smaller diameter orifice. It is impossible toconstruct a punch which will successfully perform the operation ofextruding the ma terial of the billet through the finishing ori-Accordin to the present method the die 1 is forms with a recess 2 of adiameter sligitly greater than the billets that are use The bottomwall 3of this die converges to the diameter of the orifice 4 which is the fulldiameter of the finished tube.

The billets 5 used are of cylindrical form is a pilot 8 which is thesame diameter as the inner diameter of the finished tube and is adaptedto extend axially through the orifice 4 to form a throat through whichthe metal of the billet is forced.

Inthe forming of a length of tube in this die a heated billet is placedin the die and the punch is moved downwardly until the pilot extendsthrough the central orifice thereof and the end of the punch closes thegie access,- the pilot extending into the orice y A continued movementof the punch. causes the metal of the billet to flow around the pilotand inwardly in the convergent die recess to the throat surroundin thepilot.

The method thus forms a tu e of the de sired diameter and thickness. v

The punch which is shown square across the bottom end in order to obtainthe proper result in the flowing of the metal of the billet, cannotfollow the metal past the upper shoulder of the tapered end of therecess,

consequently the metal is not completely extruded.

An annular recess 9 is formed in the side wall of the die recess whichvretains a narrow rib of the upper edge of the metal of the partlyextruded tube and this rib of metal forms a positive lock to holdthepartly finished tube in the die allowing the withdrawal of the punch andits pilot clear there from.

After the punch has been withdrawn 9. suitable torch 1O swings over thedie recess and a flame is directed downwardly against the upper end ofthe partly extruded tube. This flame which may be very hot is con-'tinued for a suflicient length of time to maintain the desiredtemperature of the upper part of the metal and the torch is thenwithdrawn and another heated billet is dropped into the die. The punchthen descends into the die and the force exertedagainst the billet firstcauses the metal of the former billet to flow until the tube iscompletely extruded. The punch continuing further to descend causes thenext billet to be extruded in a similar manner to the foregoing one.

The process thus described is continued indefinitely, each billet beingreheated inthe die following the initial extrusion of the major portionthereof.

This method of manufacturing short length tubes has proven to be verysuccessful i and the cost of manufacture is reduced to the minimum.

What I claim as my invention is 1. A method of extruding metal tubes,

5 consistin in placing a heated billet in a die,

then part y extruding the same from the die, by means of a punch, thenwithdrawing the punch, leavin the partly extruded billet in place, thenre ieating the unextru-ded portion 1 of the metal, then placing a heatedbillet in 15 partial extrusion of said heated billet. t

2. A method of extruding metal tubes,

consisting in placing a heated billet within a die having a taperinthroat, then a plying pressure to force t e metal of the lllet throughthe throat, then directing a flame into the die toimpinge against theunextruded end of the billet, then inserting another heated billet onthe top of the unextruded portion of the former billet, then applyingpressure to the latter billet to force the heated extruded metal of thepreceding billet through the throat of the die to complete the extrusionof the first mentioned billet andefiect a partial extrusion of thefollowing billet.

JOHN WYOLIFFE LEIGHTON.

